This study aims to develop a quantitative model to explain secular trends and differences in fertility in rural areas in the United States and Canada since 1800. The model to be tested relates fertility, measured by the child-woman ratio, to the "economic stress" experienced by young adults, conceived as the relation between economic opportunities and desired levels of living. Responses to economic stress alternative to fertility change are also considered, such as migration or agricultural improvement, with a view to identifying the conditions under which the response takes the form of fertility decline versus alternative possibilities. For the United States the principal unit of analysis will be the state, especially those which remained primarily rural; for Canada, the county. Where appropriate, population sub-groups, e.g. by color and nativity, will be distinguished. The primary source of data is the population and economic censuses and secondary works based on them. The basic data on fertility, migration, and economic change will be mobilized, various measures of economic stress will be explored, the time series and cross section patterns of association among these measures identified, and the conditioning factors which shape the weight of different responses studied.